Multicore high tension cable



Aug. 8, 1933. c. CREMER 15 2 5 MULTIUORE HIGH TENSION CABLE Filed July9. 1930 2 Sheets-Sheet 1 awe, 5W

0 bwmnwm Aug. 8, 1933. C CREMER I 1,921,606

MULTICORE HIGH TENSION CABLE Filed July 9, 1930 2 Sheets-Sheet 2Patented Aug. 8 1933 UNITED STATES MULTICORE HIGH TENSION CABLE- CarlCremer, Copenick-Wendenschloss, near Berlin, Germany Application July 9,1930, Serial No. 466,655, and

5 Claims.

When twisting together single-core cables 'so as to form multi-corecables, of which the individual conductors are of round cross sectionalarea, it is a known fact, that between the individual conductorstriangular gusset spaces are formed which, in order to ensure a roundtotal crors section of the cable, are filled up with packing materialconsisting of jute, paper or the like. In cables with a common leadsheath this packing is not subjected to the influences of the moistureof the ground or, in other words, it is protected. In cables, however,formed by twisting together a plurality of single-core cables, of whicheach one is encased in a lead sheath, 9. common lead sheath is, as arule, dispensed with. In view of the fact, that the'ordinary armouringand jute covering will not be capable of preventing with absolutecertainty the penetration of moisture, the packing in this case is ex-'posed to the risk of gradual perishing, if the cable is embedded inmoist ground.

In accordance with the present invention, this drawback will beobviated, by filling up the gusset spaces formed when twisting theseparate lead covered cables together, with lead tubes lying closelyagainst the circumference of the separate cables and of the armouring.In connection herewith it will be possible to fill up the interior ofthese lead tubes with a filling material such as jute, paper or thelike.

The cable in accordance with the present invention is suitably made insuch a manner, that the lead tubes used for filling up the gussetspaces, possess a circular cross sectional area.

prior to the twisting operation and are pressed into segmental shapeonly during the twisting operation by the nipple finally ensuring acircular total cross sectional area of the cable...

In conjunction with girdle insulation and common lead covering it hasbeen suggested to enclose the filling up packing in metallic layers forthe purpose of rendering harmless the tangential tensions met with insuch cables upon the surface of the individual conductors. A protectionof the packing against the penetration of moisture is not intended inthis case, in view of the fact, that the common lead covering rendersthe whole of the interior of the cable moisture-proof.

Apart from the protection of the packing against moisture, theconstruction of the cable according to the present invention, embodies'still further advantages. In consideration of the fact, that thepacking tubes are lying snugly against the lead covering of the separatetwisted Germany November 1, 1928 "cable conductors, they assist thecarrying oil of heat of the latter, especiallyalso in a radialdirection, as the segment-like surfaces of, the packing tubes directlyadjacent the cable circumference conduct the heat in an outwarddirection to a considerable degree. These surfaces further offer aconvenient rest for the armouring surrounding the cable- It is knownthat, as a rule, a layer of jute is placed between the iron armouringand the cable, in order to prevent the armouring being pressed into thelead covering of the conductors. It now the lead. tubes used as. packingfor the gusset spaces are made to be of such dimensions, that after thetwisting the external segments of these tubes are projecting a shortdistance above the circle described by the three conductors, everypossibility of pressure of the iron armouring upon the cable conductorswill be obviated with absolute certainty, since the radial pressurescaused by the armouring are taken up by the segments of the packingtubes and are distributed over the whole of the cable. The layer of jutebelow the armouring may, for this reason, be extremely thin, forinstance, it will' be possible to make use of one jute tape only forholding together the conductors, thus considerably improving the heatconducting properties of the loadedcables, thereby attaining at an equaladmissible temperature in the interior of the cable a higher loadcapacity.

Fig. 1 illustrates in a three-core cable the position of the three cableconductors and the packing strands, prior to their introduction into thetwisting nipple; 1 represents the three conductors. 2 the insulatinglayers and 3 the lead covering of the individual cables. These leadcoverings may, in order to increase. the margin of safety in regard toabsolute tightness and protection against the consequences of porousplaces accidentally present in the lead coverings, each consist of twoor more coverings pressed upon each other, each covering being 5 coatedwith a packing layer consisting of compound mass or the like prior topressing one covering upon the previous one. .The round packing strands5 are surrounded by thin lead coverings .4. a

Fig. 2 represents the cross sectional area of the finished cable. Thepacking strands 5 together with their lead coverings 4 have been pressedinto the triangular gusset spaces, yielding a circular total crosssectional area of the cable. v

-Qwing to the fact, that the lead coverings they may easily be made toassume the triangularshape of the gusset without collapsing, the filling5 may be omitted. In this case the gusset spaces represent hollowchannels adapted for the passage of a cooling medium.

-7 is the external iron armouring and 6 the thin intermediate'layer ofjute or the like. 8 is the usual layer of jute placed over the armouring7.

Fig. 3 shows a modification of the" cable according to the invention, inwhich the hollow spaces are used for accommodating testing andsignalling wires or the like 9.

Instead of so choosing the cross sectional area of the packing tubesthat their contours are formed of three circular segments, the crosssectional area may be such, as shown in Fig. 4, where only the twosurfaces 11, lying closely against the conductors, have the shape of acylinder segment, whilst a straight surface 12 is formed in the outwarddirection against the armouring. The cross section of the whole of thecable will then have the shape of atriangle with rounded off corners 13.

Having now particularly described and ascertained the nature of my saidinvention, I declare that what I claim is:--

1. A multi-core high tension cable comprising a combination 01' aplurality of single core cables twisted together and surrounded by anamouring permeable for liquids, each individual single core cableconsisting of a conductor, an insulation surrounding said conductor anda lead sheath surrounding said insulation, and lead tubes with wallsimpermeable for liquids, lying with walls impermeable tor liquids lyingin and filling up the-valleys between the single core cables and thearmouring and resting closely against the circumference of theindividual cables and the armouring and a filling material filling upthe interior of the said lead tubes. I

3. A multi-core high tension cable comprising a combination of aplurality of" 'single core cables twisted together and surrounded by anarmouring permeable for liquids, each individcables and the armouring,said lead tubes having arched triangular shape and projecting in thecross-sectional area radially beyond the circle circumscribing thesingle core cables.

- 4. A multi-core high tension cable-comprising a combination of aplurality of single corecables twisted together and surrounded by anarmouringpermeable for liquids, each individual single core cableconsisting of a conductor, an insula' tion surrounding said conductorand a lead sheath surrounding said insulation, lead tubes with wallsimpermeable .for liquids lying in and filling up the valleys between thesingle core cables and the armouring and resting closely against thecircumference of the individual cables and the armouring, a fillingmaterial filling up the interior of said lead tubes and testing andsignalling wires embedded in the said filling material.

5, In manufacturing a moisture-proof multicore cable the method oftwisting together a plurality of single core lead covered cables andanequal number of round tubes of soft lead in a twisting-machine, each ofsaid round tubes in passing through the twisting-machine being deformedto a substantially triangular cross-sec-' tion equal in size and shapeto the space between any two of the single core cables and the circlecircumscribing the single core cables.

CARL CREMER.

